Pulsed neodymium yttrium aluminium garnet (NdYAG) lasers are widely used in industrial processes such as welding, cutting and marking. Care has to be taken in these processes to ensure that the plasmas generated by the laser does not interfere with the incoming laser pulses. The relatively low pulse repetition rates (6 kHz) at high peak powers that are achievable in a NdYAG laser have led to their wide application in laser machining.
Fibre lasers are increasingly being used for materials processing applications such as welding, cutting and marking. Their advantages include high efficiency, robustness and high beam quality. Examples include femtosecond lasers for multiphoton processing such as the imaging of biological tissues, Q-switched lasers for machining applications, and high-power continuous-wave lasers. Their disadvantage is their relatively low energy storage capacity as compared to NdYAG lasers. For this reason, the pulse repetition frequency at high peak powers is relatively high (20 kHz) as compared to NdYAG lasers.
In many applications, fibre lasers need to compete with the more mature diode pumped solid state lasers. In order to do so, much greater optical powers need to be achieved, with high reliability and lower cost.
An aim of the present invention is to provide an apparatus for providing optical radiation that reduces the above aforementioned problems.